• 전기의세계
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• 제21권3호
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• pp.19-30
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• 1972

This paper deals with an analytic design of feedback regulator and signal state estimator in discrete linear systems. On the way of developing the deadbeat regulator, some necessary conditions for control policy have been derived, it is proved that the q periods delay in the control causes q periods delay in the point at which deadbeat response occurs. We have derived some relations such that the eigenvalue of system plant can be arbitrarily changed by the characteristics of minor loop compensator which is introduced in feedback path. And also we show that the signal state estimator which estimates the state of given signal sequence must satisfy some conditions. Theorems and conclusions are described with some simplel nontrivial numerical examples and signal state tracking application problems.

• 항공우주기술
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• 제9권1호
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• pp.98-105
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• 2010

고속푸리에변환(Fast Fourier Transform)은 이산푸리에변환(Discrete Fourier Transform)의 주기적으로 반복되는 연산을 생략하여 그 속도를 향상시킨 연산방법이다. Radix-2 FFT는 그 정의에 따라 함수 재귀호출에 의해 구현될 수 있는데 이 방법은 스택복사 과정의 시간소모 때문에 고속동작이 어렵게 된다. 이를 극복하기 위해 신호점을 연산순서에 맞게 미리 재배열하고 배열된 신호점을 나비연산하는 방법으로 고속연산을 구현할 수 있다. 이 논문은 신호점 재배열 방법에 의한 Radix-2 FFT의 고속연산에 착안하여 Radix-3 FFT에 신호점 재배열 방식을 적용해 보고 그 타당성에 관해 고찰하였다.

• 한국통신학회논문지
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• 제41권11호
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• pp.1380-1386
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• 2016

본 논문에서는 BPSK변조를 사용하는 OFDM(Orthogonal Frequency Division Multiplexing)기반의 시스템에서 2 branch로 나눈 후에 DCT(Discrete Cosine Transform)를 사용하고 DHT(Discrete Hilbert Transform)와 복소수를 이용하여 스펙트럼을 변화시켜 SSB(Singe Side Band) 전송과 같은 효과를 내는 시스템 모델을 제시하고 성능을 평가한다. 또한 제안하는 시스템은 한 정보신호를 SSB전송과 같이 절반의 스펙트럼으로 송신을 할 뿐만 아니라 전체의 스펙트럼을 양측파대라 할 때 양측파대 중 한쪽의 단측파대를 통해 BPSK 변조된 하나의 정보신호를 다른쪽의 단측파대를 통해 다른 BPSK 변조된 정보신호를 동시에 송신하고 수신기에는 하나의 OFDM시스템의 신호처럼 들어온 신호에서 양측파대 각각에서 정보신호를 구분 복조 한다. 또한 각각의 복조된 BPSK 신호는 이론적인 BPSK신호와 거의 유사한 BER 성능을 보인다. 즉 제안하는 시스템 모델은 하나의 BPSK신호를 절반의 스펙트럼만을 사용하여 송신하거나 혹은 두 BPSK신호를 동시에 송신 할 수 있다.

• 한국통신학회논문지
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• 제22권11호
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• pp.2488-2497
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• 1997

본 논문에서는 카오스 현상을 발생시키는 이산 로렌츠 시스템의 컴퓨터 모의 실험에 대한 방법을 제시하였다. 모의 실험에서의 카오스적인 움직임은 수치해석에 의해 예측된 결과와 일치하였다. 동기화된 카오스 시스템의 원리를 사용함으로써, 비화통신을 위한 접근 방법 로렌츠 방정식을 코딩한 송.수신기를 컴퓨터를 사용, 모의 실험함으로써 증명하였다. 송신기에서는 카오스 신호를 사용해서 보내고자 하는 메시지를 먼저 카오스 신호와 곱하고 다시 카오스 신호를 더해서 전송한다. 한편 수신기에서는 전송된 신호를 수신측 카오스 신호로 빼준 후에 다시 나누어서 전송된 메시지를 회복하는 방법을 사용하였다. 비선형 상태추정으로써 로렌츠 이산 카오스 동기 시스템의 견고성의 정도를 결정하기 위해서 샘플링 시간을 달리했으며, 이때 동기 오차와 그에 따른 송신신호와 수신신호와의 오차 값을 비교하여 성능을 평가하였다.

• 대한전자공학회논문지
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• 제21권6호
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• pp.70-77
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• 1984

This paper represents a fast computational algorithm for the discrete sine transform defined by Kekre and Solanki. Techniques are developed to factor the discrete sine trans form matrix into M=log2 2N matrices, where the number(N) of sampled data points is a power of two. Each factorial matrix contains not more than two non-zero real elem tints in any row or column. As a result of this method, the exact a배orithm for the fast discrete sine transform is accomplished. The algorithm is illustiated by a signal flow graph, which may be readily translated to hardware or software implementation.

• 디지털산업정보학회논문지
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• 제11권1호
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• pp.171-182
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• 2015

The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

• Journal of Information Processing Systems
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• 제8권4호
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• pp.669-684
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• 2012

Discrete wavelet transforms are extensively preferred in biomedical signal processing for denoising, feature extraction, and compression. This paper presents a new denoising method based on the modeling of discrete wavelet coefficients of ECG in selected sub-bands with Kernel density estimation. The modeling provides a statistical distribution of information and noise. A Gaussian kernel with bounded support is used for modeling sub-band coefficients and thresholds and is estimated by placing a sliding window on a normalized cumulative density function. We evaluated this approach on offline noisy ECG records from the Cardiovascular Research Centre of the University of Glasgow and on records from the MIT-BIH Arrythmia database. Results show that our proposed technique has a more reliable physical basis and provides improvement in the Signal-to-Noise Ratio (SNR) and Percentage RMS Difference (PRD). The morphological information of ECG signals is found to be unaffected after employing denoising. This is quantified by calculating the mean square error between the feature vectors of original and denoised signal. MSE values are less than 0.05 for most of the cases.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.225-230
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• 1997

Discrete Wavelet Transforms (DWTs) are recent mathematics, and begin to be used in various fields. The wavelet transform can be used to compress the signal and image due to its inherent properties. We applied the wavelet transform compression and reconstruction to the neutron cross section data. Numerical tests illustrate that tile signal compression using wavelet is very effective to reduce the data saving spaces.

• ETRI Journal
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• 제28권2호
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• pp.250-252
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• 2006

In this letter, a discrete state, discrete time chaotic pseudo random number generator (CPRNG) is presented for stream ciphering of text, audio, or image data. The CPRNG is treated as a finite state machine, and its state is modulated according to the input bit sequence of the signal to be encrypted. The modulated state sequence obtained can be transmitted as a spread spectrum or encrypted data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.336-338
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• 2004

This paper introduces a compression algorithm for power quality disturbance signal via the discrete wavelet transform, DWT. Fundamental signal or stationary signal is estimated and then subtracted from a given signal to obtain a difference signal or nonstationary signal. DWT is applied to a difference signal to get coefficients that are thresholded to reduce a number of coefficients. Simulation results show the resonable compression ratio while keep low signal distortion.